What ‘—‘ means in an Aldi comparison

This means that we cannot find sufficient products in Aldi that match the ones you have selected in your chosen store. Aldi have far fewer products than the other stores so often there isn’t a close match to a product from another retailer. This happens in reverse too – if you start your shop with Aldi you may notice “unavailable” against one or more of the retailers in the comparison summary. This happens for the same reasons.